A thermal management system with the capability of achieving excellent heat dissipation is essential to the development of battery pack for transportation devices. To meet the temperature uniformity requirements of the battery pack, the plate flat heat pipe and liquid-cooled coupled multistage heat dissipation system had been introduced. In this article, the research status of thermal management systems in battery pack was introduced. And the heat generation and heating power of the Li-ion cell were studied. Then, the structure model of plate flat heat pipe system was proposed. Finally, the enhanced heat conduction effect of the thermal management system proposed in this article was comprehensively analyzed. Through the analysis of the results, in high discharge rates, the thermal management system proposed in this article could meet the temperature uniformity requirements of battery pack; also, the internal difference would reduce by 30.20%.